HighMechanical grinding of pavement to remove line markings generates high concentrations of respirable crystalline silica (RCS) dust from the asphalt or concrete pavement surface. The diamond grinding wheels pulverize the pavement into extremely fine particles including crystalline silica, which becomes airborne and can be inhaled by workers. Even with water suppression, significant dust generation occurs, particularly in dry conditions or when water application is inadequate. Respirable silica particles are less than 10 microns in diameter - invisible to the naked eye - and penetrate deep into lung alveoli where they cannot be cleared by normal respiratory defence mechanisms. Once lodged in lung tissue, silica particles trigger inflammatory responses that lead to progressive fibrosis (scarring) of lung tissue. This condition, silicosis, is irreversible and incurable. Early-stage silicosis may be asymptomatic but progresses to cause shortness of breath, persistent cough, fatigue, and in advanced cases, respiratory failure requiring oxygen therapy or lung transplant. Silica exposure also increases risk of lung cancer, tuberculosis, chronic obstructive pulmonary disease, and kidney disease. The latency period between exposure and disease onset can be 10-20 years, meaning workers may develop silicosis years after exposure ceases. Australian workplace exposure standards limit respirable crystalline silica to 0.05 mg/m³ eight-hour time-weighted average - a level easily exceeded during uncontrolled grinding operations.
HighRoad line markings applied before 1997 may contain lead-based paint, with lead concentrations potentially exceeding 1% by weight. When these lines are ground or abraded, lead particles become airborne or are dispersed in the water slurry generated during wet grinding. Workers can inhale lead dust, ingest lead particles through hand-to-mouth contact, or absorb lead through skin contact with contaminated slurry. Lead is a cumulative poison that accumulates in bone, blood, and soft tissues, causing irreversible damage to the nervous system, kidneys, and reproductive system. Neurological effects include cognitive impairment, memory loss, mood changes, tremor, and peripheral neuropathy. Lead exposure causes kidney disease that may progress to kidney failure requiring dialysis. Reproductive effects include reduced fertility, miscarriage, and developmental delays in children of exposed workers. Lead readily crosses the placental barrier, making pregnant workers particularly vulnerable. There is no safe level of lead exposure - any exposure carries health risk. The workplace exposure standard for inorganic lead is 0.05 mg/m³ time-weighted average, with biological exposure limits of 30 μg/dL blood lead level for most workers (lower for women of reproductive capacity). Grinding lead-containing lines without appropriate controls can generate exposures orders of magnitude above these limits.
MediumChemical removal of line markings involves application of paint strippers, solvents, or chemical agents designed to dissolve or soften marking materials for easier removal. These chemicals commonly contain methylene chloride, methanol, acetone, toluene, or other volatile organic compounds that evaporate rapidly creating toxic vapours. Workers applying chemicals or working near treated surfaces can inhale vapours causing respiratory irritation, dizziness, headaches, nausea, and at high concentrations, loss of consciousness. Skin contact with chemical strippers causes chemical burns, dermatitis, and systemic absorption of toxic substances through intact or damaged skin. Eye contact causes severe irritation and potential corneal damage. Methylene chloride is metabolized in the body to carbon monoxide, reducing blood oxygen-carrying capacity and causing cardiac stress - particularly dangerous for workers with pre-existing heart conditions. Prolonged or repeated exposure to organic solvents is associated with liver and kidney damage, neurological effects including memory impairment and coordination problems, and increased cancer risk. Chemical vapours are heavier than air and can accumulate in low-lying areas or confined spaces, creating localized high-concentration zones. The odour threshold for many solvents is below the concentration that causes health effects, meaning workers may be overexposed even when odours seem tolerable.
MediumWater suppression during grinding and the removed marking material create wet, slippery conditions on the pavement surface where workers operate. The slurry of water, paint or thermoplastic particles, and pavement fines forms a coating on the road surface that significantly reduces friction. Workers walking on this surface while operating equipment, managing hoses, or performing other tasks face serious slip hazards, particularly when wearing smooth-soled footwear or when moving quickly. Thermoplastic line marking material is particularly hazardous when ground as the heat from grinding can partially melt the thermoplastic, creating extremely slippery, oily residues. Slip incidents can result in workers falling onto hard pavement surfaces causing injuries including wrist fractures from attempting to break falls, hip fractures, head injuries from striking pavement, and soft tissue injuries to backs and shoulders. Slips occurring in active traffic lanes create additional danger as fallen workers may be in the path of approaching vehicles. The risk increases at night when wet surfaces reflect light creating glare that obscures surface conditions. Chemical removal methods using solvents also create slippery conditions as dissolved paint or thermoplastic forms an oily film on the pavement. Workers may not recognize slip hazards when focused on operating equipment or watching for traffic.
HighTraffic line removal occurs on operational roads where vehicles continue to travel, creating constant risk of vehicle strike. Workers operating grinding equipment, managing water hoses, or collecting removed material must work in or immediately adjacent to traffic lanes where vehicles may be traveling at speeds of 60-110 km/h depending on road classification. Despite traffic management controls including signs, delineation, and traffic controllers, some motorists fail to slow, become distracted, or drift into work zones. Line removal equipment operators may face away from traffic while focusing on grinding operations, reducing their awareness of approaching vehicles. The noise from grinding equipment and requirement to wear hearing protection further reduces workers' ability to hear approaching vehicles or warning calls from colleagues. Night works, which are common for line removal to minimize traffic disruption, compound the hazard as worker visibility is reduced despite high-visibility clothing. Fatigue affects both workers and motorists during night shifts, degrading reaction times and decision-making. The relatively slow travel speed of line removal equipment (typically 5-20 km/h) means workers spend extended periods exposed to traffic in each work zone location.
